Hydraulic analysis of gate valve using computational fluid dynamics (CFD)

Abstract

As a very important element of most water supply systems, valves are exposed to the effects of strong hydrodynamic forces. When exposed to large physical quantities, the valve and piping can be damaged, which could endanger the performance of a water supply system. This is the main reason why it is necessary to foresee and determine the maximum values of velocity, pressure and other physical quantities that can occur in the system under certain conditions. Predicting extreme conditions allows us to correctly size the valve for the expected conditions to which the valve might be exposed, which is also the main objective of this paper. One of the methods for predicting and determining extreme values on a valve is to perform a simulation with computational fluid dynamics (CFD). This is exactly the method used in the preparation of this paper with the aim of gaining insight into the physical magnitudes for models of gate valves positioned inside a pipe under characteristic degrees of valve closure. The Ansys CFX 19.1 and Ansys Fluent 19.1 software was used to simulate the hydrodynamic analysis and obtain the required results. The hydrodynamic analysis was performed for four opening degrees of gate valve

Full text

Hydraulic analysis of gate valve using computational fluid dynamics (CFD) 275
Key words: gate valve, hydrodynamic analy-
sis, CFD, Ansys Workbench software package
Introduction
The water supply network consists
of a number of interdependent elements,
one of which is a gate valve. They re-
present machine elements commonly
used to control fluid flow because they
provide positive seal at high liquid and
gas pressures (Fig. 1). They are used in
various industries such as refineries, pe-
trochemical plants, power stations, hy-
droelectric power plants, nuclear power
plants, etc. High flow velocities with
partial opening of the valve can lead to
erosion of its walls, vibrations and noise
(Banko, 2019). They are most commonly
used for drinking water and wastewa-
ter in the temperature range from –20 to
+70°C and can withstand flow velocities
of up to 5 m·s–1 and pressures of up to
16 bar. Their main disadvantage is the
large required number of turns of the
valve opening/closing handwheel.
During the opening or closing of
the gate valves, considerable forces are
exerted on the valve construction due to
the leakage of the flow. The hydrodyna-
mic forces caused by the high flow ve-
locities under the gate valve result in a
vertical force downwards. As the gate
valve opens, the velocities increase non-
-linearly in relation to the degree of open-
ing. Most flow changes occur near the
valve at a relatively high flow velocity
and cause wear on the valve walls and
bearings. High flow velocities in par-
tially opened valves can cause erosion
of the valve discs and the bearings them-
selves, and vibrations can cause dama-
ge to the partially opened disc (Quimby,
2007). When the gate valve is lowered to
reduce the flow (e.g. by closing), the pres-
sure on the lower surface of the valve de-
creases due to the high flow velocity,
PRACE ORYGINALNE
ORIGINAL PAPERS
Scientific Review – Engineering and Environmental Sciences (2020), 29 (3), 275–288
Sci. Rev. Eng. Env. Sci. (2020), 29 (3)
Przegląd Naukowy – Inżynieria i Kształtowanie Środowiska (2020), 29 (3), 275–288
Prz. Nauk. Inż. Kszt. Środ. (2020), 29 (3)
http://iks.pn.sggw.pl
DOI 10.22630/PNIKS.2020.29.3.23
Elvis ŽIC1, Patrik BANKO1, Luka LEŠNIK2
1University of Rijeka, Faculty of Civil Engineering
2University of Maribor, Faculty of Mechanical Engineering
Hydraulic analysis of gate valve using computational fluid
dynamics (CFD)

276 E. Žic, P. Banko, L. Lešnik
while the pressure on the upper surface
of the valve changes only slightly relative
to the static regime. The aim of this paper
is to apply computational fluid dynamics
(CFD) to gain insights into the physical
quantities for gate valve models within
a pipe at characteristic opening degrees.
By comparing the results of models with
different degrees of opening of the gate
valve, a more accurate and better quality
of the observed pipeline components can
be guaranteed.
Previous research
Numerous studies have been carried
out on gate valves, only some of which
are listed below. Jatkar and Dhanwe
(2013) carry out stress analyses on cri-
tical components of gate valves using
the FEA technique. The modelling of
valve components was performed in the
CATIA V5R17 software and analysed
with the FEM method in the ANSYS-
-11 software. The validation of the soft-
ware results is analytically supported by
a stress analysis using the classical theory
of solid mechanics. Patil and Gambhire
(2014) provide a basic methodology for
the design of gate valve bodies using a
CAD technology where structural FEM
analysis is applied at maximum operating
pressure. The work involved static, dyna-
mic, thermal, harmonic and electromag-
netic analyses on a valve using CATIA
and Ansys Fluent software. The work of
Wang (2014) is based on the CAD/CAE
a b
FIGURE 1. Gate valve: a – cross-section (1 – body, 2 – bonnet, 3 – solid wedge, 4 – body seats,
5 – stem, 6 – back seat, 7 – gland follower, 8 – gland flange, 9 – stem nut, 10 – yoke nut, 11 – hand-
wheel, 12 – handwheel nut, 13 – stud bolts, 14 – nuts, 15 – stud bolts, 16 – nuts, 17 – bonnet gasket,
18 – lubricator, 19 – packing); b – model with solid wedge (Banko, 2019)

Hydraulic analysis of gate valve using computational fluid dynamics (CFD) 277
system. The influence of factors such as
fluid flow, flow velocity, wall thickness
of the valve body and transverse instal-
lation was investigated in the paper.
Pujari and Joshi (2016) carried out the
analysis and optimization of the design
of gate valve bodies using the FEA tech-
nique and stress analysis. Katkar, Kul-
karni, Patil and Katkar (2017) analysed
the critical components of a gate valve.
The paper gives a detailed overview of
the different techniques used in the de-
sign of gate valves (developed in CATIA
software) and the analysis in the ANSYS
Workbench software package using the
FEM technique.
Application of numerical models
For the calculation and hydraulic
analysis in this paper the Ansys CFX 19.1
and Ansys Fluent 19.1 software with-
in the Ansys Workbench software pack-
age was used (Ansys CFX 15.0, 2015,
Žic, 2019). The following part describes
the design of a numerical model of a gate
valve using the Ansys CFX 19.1 soft-
ware and the definition of the water sup-
ply pipe and the valve around which the
fluid flows. The water supply pipe and
the 3D geometric model of the gate valve
were created in the AutoCAD 2016 soft-
ware for a starting position of 20% pipe
closure. The water supply pipe has a dia-
meter of 100 mm, while the thickness of
the pipe and valve flange is 1 mm. Defin-
ing and importing the pipe system geo-
metry is done in the SpaceClaim and De-
signModeler software packages within
the software Ansys Workbench packa-
ge (Banko, 2019). For the initial model
with a 20% of the valve opening a pipe
length of 820 mm was taken (300 mm in
front of the valve and 520 mm behind the
valve), because the changes are larger
and longer in the span behind the gate
valve. The DesignModeler software was
used to generate the network model of
the gate valve. After mesh generation, it
is necessary to check the quality of the
numerical mesh to ensure that a mean-
ingful result is obtained during pro-
cessing (Žic, 2019). It is also necessary
to define all the contour elements of the
future model (e.g. inlet and outlet pro-
file, pipe walls, valve, etc.). The network
consists of 101,205 nodes and 502,984
elements. In addition to checking the
quality of the numerical grid, the qual-
ity of the elements was also checked by
checking the aspect ratios for the tri-
angle, prism and tetrahedron, the Jaco-
bian ratio or “Jacobian”, the twist factor,
the characteristic length of the element,
etc. For processing, it is necessary to
define physical parameters for a given
numerical model/submodel, including
the definition of the input variables and
their values, the definition of a model
type, the definition of the dynamic and
kinematic viscosity and the initial and
boundary conditions. A single-phase
problem is selected, which means that
only one fluid is defined in the problem
(water at 25°C). For the hydrodyna-
mic analysis, a stationary flow regime
with a reference pressure of 101,325 Pa
without heat transfer within the model
and the so-called k–ε turbulence
model with standard wall function was
chosen. The first variable (k) represents
the turbulent kinetic energy and the
second transport variable (ε) refers to the
dissipation rate of the turbulent kinetic
energy. The transport equation for k is

278 E. Žic, P. Banko, L. Lešnik
described by the expression (1) and the
transport equation for ε by the expres-
sion (2) (Ansys CFX 15.0, 2015):
()
jj
i
tiji
tk b M
k
ii
UU
U
Dk
Dt x x x
kGY S
xx
ρμ
μμσ ρε
§·
∂∂
∂
=+ +
¨¸
¨¸
∂∂∂
©¹
½
∂∂
++ −+−+
®¾
∂∂
¯¿
(1)
13
2
2
()
jj
i
tb
iji
t
ii
UU
U
DCCG
Dt k x x x
CS
xxk
εε
εεε
εε
ρμ
εε
μμσ ρ
ªº
§·
∂∂
∂
§·
=+++
«»
¨¸
¨¸ ¨¸
∂∂∂
©¹
«»
©¹
¬¼
§·
½
∂∂
++ − +
¨¸
®¾
¨¸
∂∂
¯¿
©¹
(2)
The turbulent viscosity μt is defined
by the expression
2
t
k
C
μ
μρ ε
=
where ρ
is the density of the liquid. The veloci-
ties Ui and Uj define the velocities in the
longitudinal and transverse cross section
of the flow. The coefficients σk, σb, C1ε,
C2ε, C3ε and Cμ are the empirically de-
fined constants. With the marks Gb,
YM, Sk and Sε within the expressions (1)
and (2) are presented the values of the
variables with which we can model the
turbulence. The compressibility effects
are denoted by YM, the buoyancy force
by Gb and user-defined sources by Sk and
Sε. The compressibility effects are mainly
due to large changes in the properties and
characteristics of the fluid. Their influ-
ence is described by the coefficients βc
and β*c as a function of the Mach num-
ber by the following expressions (Decaix
& Goncalvès da Silva, 2013):
** *
(1 ( ))
ct
FM
ββ ξ
=+
(3)
**
()
ct
FM
βββξ
=−
(4)
22
00
()( )( )
ttt tt
F
MMMHMM=− −
(5)
for the values Mt0 = 0.25 and ξ* = 1.5.
An initial inlet flow velocity of 1.0 m·s–1
is defined for the inlet profile on the
surface of the entire inlet profile, while
a relative pressure of 0 Pa is defined on
the outlet profile. This means that at the
last profile of the water supply pipe the
pressure is equal to the pressure outside
the pipe (atmospheric pressure). In the
post-processing part of the numerical
modelling, arbitrary transverse and lon-
gitudinal profiles are selected, on the ba-
sis of which changes of certain physical
quantities within the obtained model can
be represented. The gate valve was ana-
lysed by four positions: 20, 40, 60 and
80% of the valve closed. For each of
these submodels a hydrodynamic analy-
sis of the fluid flow around the valve at
an inflow velocity of 1.0 and 1.5 m·s–1
was performed.
Hydrodynamic analysis
and research results
The processed variants were com-
pared for each physical quantity, name-
ly flow velocity (v), relative pressure (p)
and turbulence kinetic energy (k). Each
of the physical quantities is calculated
using the same eight transverse (Fig. 2)
and nine longitudinal profiles. The trans-
verse profiles are arranged in such a way
that the first one is halfway between the
start of the pipe and the valve, the second
one directly in front of the valve, the
fourth profile runs through the middle of
the valve, the next three profiles are di-

Hydraulic analysis of gate valve using computational fluid dynamics (CFD) 279
rectly behind the valve and the last one
halfway between the valve and the end
of the pipe. The longitudinal profiles are
positioned so that the middle fifth pro-
file is in the middle of the pipe and the
four longitudinal profiles are symmetri-
cally arranged at equal distances on both
sides.
Fluid flow velocity
Figure 3 shows a longitudinal view of
the gate valve model at various degrees
of opening based on the 150 streamlines.
The first four models show models with
an inlet velocity of 1.0 m·s–1 and the
last four models with an inlet velocity of
1.5 m·s–1.
The figure shows that a vortex flow
is observed in the area behind the gate
valve at 80% closure, which is a conse-
quence of the abrupt narrowing of the flow
cross-section under the valve, which also
causes the greatest increase in flow velo-
city (red colour in Fig. 3). The stream-
lines of each model are shown at local
values, i.e. the colours are not univer-
sal and are not the same on each of the
models, therefore the flow velocities on
the model cannot be compared with each
other depending on the colour tones,
but only individually (the legends gi-
ven in Fig. 3 refer to a gate valve with a
TP1
p
osition of
g
ate valve
TP2
TP7 TP8
FIGURE 2. Arrangement of the transverse profiles (TP) in relation to the gate valve
a
b
c
d
e
f
g
h
FIGURE 3. Model view of gate valves with streamlines: a – model with 20% gate closure (inlet ve-
locity v = 1 m·s–1); b – 40% closure (v = 1 m·s–1); c – 60% closure (v = 1 m·s–1); d – 80% closure
(v = 1 m·s–1); e – 20% closure (v = 1.5 m·s–1); f – 40% closure (v = 1.5 m·s–1); g – 60% closure
(v = 1.5 m·s–1); h – 80% closure (v = 1.5 m·s–1)

280 E. Žic, P. Banko, L. Lešnik
valve closing degree of 80% at velocities
of 1.0 and 1.5 m·s–1). The maximum, mini-
mum and average values of flow veloci-
ties for each of the submodels and both
inlet flow velocities are shown in Table 1.
The average and maximum flow velo-
cities within the model increase expo-
nentially as a function of the percentage
closure of the gate valve. The increment
percentages coincide with the second
decimal place and are 115.5% from 20
to 40% closed, 133% from 40 to 60%
closed and 175% from 60 to 80% closed
valve for the average values. The percen-
tages for increasing the maximum values
of the flow velocities are in the same or-
der: 162, 175 and 240%. Table 2 shows
the maximum (bold values) and average
values of flow velocities for all positions
of valve closure with inlet velocities of
1.0 and 1.5 m·s–1 up to eight transverse
profiles (Fig. 2). The positions of the lar-
gest maximum and average flow velocity
values vary depending on the percentage
of valve closure.
It is also noticeable that the values
of maximum and average flow velocities
for all profiles in the immediate vicin-
ity of the valve increase exponentially
with the percentage of closure. For mod-
els with 20% closure and an inlet flow
velocity of 1.0 m·s–1 the average valve
flow velocity is 1.03 m·s–1, for models
with 40% closure 1.40 m·s–1, with 60%
closure 2.39 m·s–1 and with 80% clo-
sure the value is 6.50 m·s–1. The maxi-
mum flow velocity of 10.4 m·s–1 occurs
at the fifth profile (directly behind the
valve) for models with an inlet velocity of
1.0 m·s–1 and 15.6 m·s–1 for models with
an inlet velocity of 1.5 m·s–1. Maximum
flow velocities with lower valve clo-
sure occur at a greater distance behind the
valve, while models with a higher valve
closing percentage have maximum val-
ues of flow velocity closer to the valve
due to the abrupt narrowing of the flow
area. The nine longitudinal profiles are
defined at regular intervals, starting from
the centre of the pipe towards the edges
(the centre of the fifth profile intersects
the centre of the valve, seen perpendic-
ular to the valve). They show most clear-
ly the change in flow velocity along the
pipe and the transient flow velocity from
the beginning of the pipe system through
the valve to the recovery of the flow ve-
locity at a certain distance behind the
valve. Table 3 shows the maximum and
average flow velocities for all positions of
valve closure with inlet velocities of 1.0
and 1.5 m·s–1 for nine randomly selected
TABLE 1. View of the maximum, minimum and average values of the flow velocities [m·s–1] for each
of the gate valve models
Percentage of gate
valve closure
[%]
v = 1.0 m·s–1 v = 1.5 m·s–1
max min avg max min avg
20 1.564 0.007 1.035 2.337 0.021 1.553
40 2.533 0.003 1.195 3.797 0.004 1.795
60 4.415 0.004 1.594 6.633 0.003 2.390
80 10.585 0.002 2.780 15.884 0.004 4.220

Hydraulic analysis of gate valve using computational fluid dynamics (CFD) 281
longitudinal profiles. The maximum av-
erage flow velocities on the defined lon-
gitudinal profiles are 1.79 m·s–1 for the
model with an inflow velocity of 1.0 and
2.67 m·s–1 for the model with an inflow
velocity of 1.5 m·s–1. Figure 4a shows
TABLE 2. View of the maximum and average values of the flow velocities [m·s–1] at a gate valve on
the corresponding transverse profiles
Cross
section
profile
20% valve closure 40% valve closure 60% valve closure 80% valve closure
max avg max avg max avg max avg
1 1.03 1.00 1.03 0.99 1.03 0.99 1.03 0.99
2 1.15 0.99 1.37 1.02 1.72 1.08 2.34 1.14
3 1.29 1.01 1.77 1.25 2.76 1.64 5.99 2.40
4 1.45 1.03 2.13 1.40 3.75 2.39 9.93 6.49
5 1.53 1.02 2.28 1.20 4.03 1.59 10.40 2.68
61.56 1.17 2.43 1.40 4.26 1.80 10.34 2.62
7 1.51 1.16 2.53 1.57 4.41 1.97 9.84 2.81
8 1.16 0.98 1.59 0.97 2.51 1.14 4.78 2.04
Cross
section
profile
20% valve closure 40% valve closure 60% valve closure 80% valve closure
max avg max avg max avg max avg
1 1.54 1.49 1.54 1.48 1.54 1.48 1.54 1.48
2 1.73 1.49 2.05 1.54 2.59 1.62 3.51 1.72
3 1.92 1.51 2.64 1.87 4.13 2.46 8.99 3.60
4 2.17 1.54 3.20 2.10 5.63 3.58 14.91 9.75
5 2.28 1.51 3.43 1.80 6.04 2.39 15.59 4.02
62.34 1.73 3.65 2.12 6.39 2.71 15.50 3.93
7 2.26 1.72 3.79 2.37 6.63 2.96 14.76 4.22
8 1.74 1.48 2.39 1.46 3.79 1.71 7.14 3.02
a
b
FIGURE 4. Graphical view of the maximum flow velocities for a gate valve model with 80% closure
based on transverse profiles (a) and longitudinal profiles (b)

282 E. Žic, P. Banko, L. Lešnik
a graphical representation of the flow ve-
locities for a gate valve model with 80%
closure at an inflow velocity of 2.0 m·s–1,
compared with the same model with an
inflow velocity of 1.0 and 1.5 m·s–1. The
maximum velocity value on the fifth
profile at an inlet velocity of 2.0 m·s–1 is
20.80 m·s–1. Figure 4b shows the values
of maximum flow velocities per longi-
tudinal profile for the model with 80%
valve closure for inlet velocities of 1.0,
1.5 and 2.0 m·s–1.
Relative pressure
The maximum, minimum and aver-
age values of relative pressures [Pa] for
all submodels of gate valves based on
the k–ε turbulent model are shown in
Table 4. The maximum, minimum and
average relative pressure values increase
exponentially when the valve is closed.
The average relative pressure of a valve
80% closed is approximately 75 times
higher than in the case of a valve 20%
TABLE 3. View of the maximum and average values of flow velocities [m·s–1] at a gate valve at the
corresponding longitudinal profiles
Longitudinal
profile
20% valve closure 40% valve closure 60% valve closure 80% valve closure
max avg max avg max avg max avg
1 1.561 1.015 2.378 1.019 3.806 0.994 2.021 0.976
2 1.559 1.002 2.522 1.027 4.160 1.110 9.816 1.325
3 1.549 0.982 2.532 1.040 4.356 1.195 10.198 1.635
4 1.551 0.981 2.529 1.042 4.383 1.208 10.347 1.702
5 1.549 0.981 2.529 1.052 4.413 1.243 10.437 1.787
6 1.545 0.981 2.528 1.044 4.390 1.213 10.264 1.700
7 1.547 0.986 1.527 1.035 4.333 1.182 10.098 1.566
8 1.553 1.002 2.521 1.027 4.160 1.116 9.911 1.337
91.563 1.016 2.405 1.026 3.946 0.997 2.022 0.971
Longitudinal
profile
20% valve closure 40% valve closure 60% valve closure 80% valve closure
max avg max avg max avg max avg
1 2.333 1.529 3.584 1.541 5.712 1.497 2.963 1.453
2 2.326 1.505 3.787 1.546 6.245 1.668 14.730 1.970
3 2.309 1.472 3.796 1.562 6.540 1.793 15.295 2.438
4 2.311 1.470 3.793 1.565 6.582 1.813 15.517 2.541
5 2.308 1.469 3.788 1.578 6.627 1.864 15.650 2.670
6 2.302 1.470 3.792 1.565 6.592 1.819 15.390 2.541
7 2.306 1.479 3.792 1.553 6.506 1.773 15.146 2.339
8 2.318 1.506 3.788 1.542 6.248 1.674 14.871 1.998
92.336 1.530 3.617 1.539 5.918 1.498 2.987 1.456

Hydraulic analysis of gate valve using computational fluid dynamics (CFD) 283
closed. The values to be analysed when
dimensioning the valve as a function of
pressure are maximum and minimum
pressures, since extreme maximum and
minimum pressures can cause the pipe it-
self to expand or twist, which can lead to
its damage and cracking. The upper row
in Figure 5 shows the changes in relative
pressures at the first four transverse pro-
files (a), b), (c) and (d) and the bottom
row shows the changes in relative pres-
sures at the last four transverse profiles
(e), (f), (g) and (h) for the gate valve sub-
model at 80% closed (at 1.0 m·s–1).
Table 5 shows the maximum, mini-
mum and average values of the relative
pressures at the transverse profiles for all
submodels of gate valves and both inlet
velocities. The highest relative pressures
and the lowest negative pressures occur
at both inlet flow velocity variants for
the same profiles. The maximum relative
pressure values are 56,942 Pa for the in-
let velocity of 1.0 m·s–1 and 127,817 Pa
for the inlet velocity of 1.5 m·s–1, which
occur for partial models with 80% valve
closure on the third profile 7 cm in front
of the disc surface of gate valve, seen in
the direction of flow. The lowest nega-
tive pressures also occur in submodels
with 80% valve closure on the fourth
profile, which is located at the back of
the valve disc.
TABLE 4. View of maximum, minimum and average relative pressures [Pa] for each of the gate valve
submodels
Percentage of gate
valve closure
[%]
v = 1.0 m·s–1 v = 1.5 m·s–1
max min avg max min avg
20 895 –1 053 171 1 983 –2 501 355
40 1 989 –2 689 407 4 433 –6 057 886
60 7 223 –8 209 1 897 16 195 –18 347 4 228
80 56 948 –46 156 12 890 127 831 –103 401 29 080
a b c d
e f g h
TP 1 TP 4
TP 3 TP 2
TP 5 TP 7 TP 8
TP 6
FIGURE 5. Distribution of the relative pressures on transverse profiles of gate valve submodels with
80% of valve closure and inflow velocity of 1.0 m·s–1

TABLE 5. The view of maximum, minimum and average values of the relative pressures [Pa] at the transverse profiles TP1 to TP8 in gate valve
model
Cross
section
profile
v = 1.0 m·s–1
20% valve closure 40% valve closure 60% valve closure 80% valve closure
max min avg max min avg max min avg max min avg
1 443 439 441 1 538 1 534 1 536 6 773 6 769 6 671 56 499 56 495 56 497
2 665 261 403 1 836 1 076 1 446 7 103 5 769 6 583 56 844 54 647 56 160
3870 123 –367 1 978 517 1 137 7 216 3 526 5 546 56 942 40 241 52 472
4 48 –58.2 –230 178 –1 548 –791 1 834 –3 759 –1 782 17 326 –13 637 –3 976
5 –21 –623 –343 –185 –1 430 –1 035 141 –3 221 –2 530 793 –9 522 –7 905
6–110
–838 –443 –674 –1 602 –1 272 –1 736 –2 412 –2 970 –5 821 –9 588 –8 699
7–174 –591 –373 –1 185 –1 844 –1 589 –3 098 –3 822 –3 579 –8 856 –10 293 –9 819
8 97 90 94 –39 –68 –54 –669 –735 –69 –3 730 –3 922 –3 807
Cross
section
profile
v = 1.5 m·s–1
20% valve closure 40% valve closure 60% valve closure 80% valve closure
max min avg max min avg max min avg max min avg
1 951 944 949 3 406 3 398 3 402 15 170 15 160 15 165 126 880 126 850 126 850
2 1 459 552 869 4 084 2 375 3 208 15 919 12 920 14 750 127 593 121 977 126 100
31 924 245 789 4 407 1 119 2 492 16 178 7 837 12 420 127 817 90 249 117 820
4 81 –1 377 –568 335 –3 549 –1 827 4 067 –8 558 –40 71 38 779 –30 978 –9 124
5 –74 –1 435 –804 –461 –3 254 –2 375 –259 –7 321 –5 755 1 715 –21 557 –17 870
6 –269 –1 830 –993 –1 563 –3 682 –2 925 –3 962 –7 750 –6 749 –13 093 –21 718 –19 650
7–415 –1 298 –843 –2 698 –4 244 –3 636 –7 016 –8 658 –8 111 –18 727 –23 214 –22 110
8 188 171 180 –188 –122 –154 –1 538 –1 686 –1 599 –8 267 –8 721 –8 446

Hydraulic analysis of gate valve using computational fluid dynamics (CFD) 285
Cavitation can occur on the part of
the pipe behind the gate valve due to ne-
gative pressures. The highest average re-
lative pressures are much higher in sub-
models with higher closure percentages
(60 and 80%) than 20% closure valve.
The value of the highest average relative
pressure at 80% closed valve is almost
120 times higher than the 20% closed
valve submodel. As the inlet velocity and
the valve closure percentage increase, an
additional increase in relative pressures
can be expected up to a certain closure
percentage when the maximum pressure
value decreases from that of the previ-
ous valve closure percentage. For proces-
sed submodels, the maximum absolute
pressure to be expected within the
pipeline is 2.29 bar at 80% closure and
an inlet velocity of 1.5 m·s–1, which is a
fully acceptable pressure for water pipes.
The maximum relative pressure for both
flow velocities occur at the middle profile
and have values of 56,948 Pa for the inlet
velocity of 1.0 m·s–1 and 127,831 Pa for
the inlet velocity of 1.5 m·s–1 (submodel
with 80% of valve closure). The highest
pressures occur in the vicinity of the
second and penultimate longitudinal pro-
file, which are 15 mm from the pipe wall.
Turbulent kinetic energy
In fluid dynamics, the turbulent ki-
netic energy – TKE (k) is a measure of
the kinetic energy per unit mass associ-
ated with eddy currents in turbulent flows.
According to the RANS equations (Rey-
nolds-averaged Navier–Stokes equa-
tions), the turbulent kinetic energy can
be calculated according to the turbulence
model. It is generally calculated as half
the sum of the variance (the square of the
standard deviations) of the velocity com-
ponents. Figure 6 shows the values of the
turbulent kinetic energy on the cross pro-
files of the submodels at 80% valve clo-
sure and an inflow velocity of 1.5 m·s–1.
The upper part of Figure 6 shows three
profiles in front of valve (a), b), (c) and
one at valve (d), and the lower part of
the figure shows profiles (e), (f), (g), (h),
which are located behind the gate valve.
The figure shows that the maximum val-
ues of the turbulent kinetic energy occur
at the valve itself and beyond, extending
from the bottom of the valve wall to the
upper half of the pipe along the flow
behind the valve. The maximum value
that appears is 2.66 m2·s–2 on the last
cross-sectional profile. The maximum
value of the turbulent kinetic energy of
5.52 m2·s–2 does not appear on any user-
-defined profile, but directly behind the
last profile (h). Table 6 shows the max-
imum (values in bold), minimum and
average values of the turbulent kinetic
energy [m2·s–2] on the transverse pro-
files for all numerical submodels and both
input velocities of 1.0 and 1.5 m·s–1.
With the increase of the valve clo-
sure degree, the maximum values of the
turbulent kinetic energy move further
away from the valve. This is due to the
increase in the variations in flow velo-
cities caused by moving away from the
valve in submodels with a smaller clos-
ing degree compared to a larger closing
degree (e.g. 60% of the valve closing
degree). For this reason, the maximum
values for submodels with higher clo-
sure percentages occur behind the last
user-defined cross-section profile in the
direction of water flow.

286 E. Žic, P. Banko, L. Lešnik
Conclusions
In this paper a hydraulic analysis of
gate valve models was performed using
the commercial softwares Ansys CFX
19.1 and Ansys Fluent 19.1. The ana-
lyses were performed for 4° of opening
of the gate valve with inlet velocities of
1.0 and 1.5 m·s–1. After the hydrodyna-
mic analysis it was found that all models
show vortices in the area behind the gate
valve, especially at smaller opening de-
grees. The appearance of the vortex and
its movement along the pipe is clearly
visible on the given central longitudinal
profiles of the pipe system. In the case of
the gate valve with 40% closing degree
and an inlet flow velocity of 1.0 m·s–1,
the maximum velocity occurring is
2.53 m·s–1, whereas for the same model
and an inlet flow velocity of 1.5 m·s–1
it is 3.80 m·s–1. The analysis shows that
maximum values of velocities, pressures
and other physical quantities occur in
models with a lower valve opening de-
gree. The maximum values of the physi-
cal quantities in the analysed models oc-
cur mainly in the valve area or behind it.
This paper shows that the implementation
of hydrodynamic analysis is possible for
different forms of valve geometry. Cor-
rect numerical modelling through CFD
technology allows the obtained results to
be used to improve the valve characteri-
stics in its design and operation.
Acknowledgements
This paper is the result of a project
on the Development of Research Infra-
structure at the University Campus in Ri-
jeka (RC.2.2.06-0001), co-funded by the
European Regional Development Fund
(ERDF) and the Ministry of Science and
Education of the Rep. of Croatia.
a b
c d
e f g h
TP 1
TP 5
TP 4
TP 3
TP 2
TP 7 TP 8 TP 6
FIGURE 6. Distribution of turbulent kinetic energy at transverse profiles of a gate valve submodel with
80% of valve closure and an inlet flow velocity of 1.5 m·s–1

TABLE 6. The view of the maximum, minimum and average values of turbulent kinetic energy [m2·s–2] on the transverse profiles TP1 to TP8
of a gate valve
Cross
section
profile
v = 1.0 m·s–1
20% valve closure 40% valve closure 60% valve closure 80% valve closure
max min avg max min avg max min avg max min avg
1 0.01144 0.00014 0.00311 0.01051 0.00014 0.00314 0.01081 0.00014 0.00313 0.01089 0.00014 0.00314
2 0.01356 0.00010 0.00308 0.01716 0.00011 0.00322 0.02147 0.00012 0.00350 0.03406 0.00014 0.00378
3 0.01497 0.00011 0.00243 0.02404 0.00016 0.00273 0.04333 0.00034 0.00384 0.14914 0.00033 0.00949
4 0.02208 0.00011 0.00565 0.05912 0.00022 0.01691 0.16759 0.00092 0.03915 0.88934 0.01319 0.21620
5 0.01968 0.00013 0.00347 0.05966 0.00033 0.01707 0.13125 0.00206 0.03468 0.53885 0.01338 0.10860
6 0.02064 0.00015 0.00482 0.09068 0.00094 0.02597 0.17000 0.00644 0.05021 0.53124 0.01730 0.13810
70.02233 0.00021 0.00503 0.18801 0.00256 0.04415 0.29017 0.01401 0.08991 0.69996 0.02282 0.20790
8 0.01337 0.00012 0.00317 0.03227 0.00321 0.01127 0.20445 0.01421 0.06462 1.14978 0.06886 0.35820
Cross
section
profile
v = 1.5 m·s–1
20% valve closure 40% valve closure 60% valve closure 80% valve closure
max min avg max min avg max min avg max min avg
1 0.02268 0.00027 0.00623 0.02073 0.00027 0.00628 0.02135 0.00027 0.00626 0.02151 0.00027 0.00628
2 0.02666 0.00021 0.00617 0.03358 0.00024 0.00642 0.04186 0.00027 0.00698 0.06617 0.00030 0.00751
3 0.02969 0.00023 0.00489 0.04692 0.00035 0.00546 0.08415 0.00074 0.00762 0.28910 0.00071 0.01871
4 0.06786 0.00025 0.01495 0.12699 0.00048 0.03366 0.33137 0.00200 0.08358 2.11641 0.02867 0.47990
5 0.06669 0.00028 0.01783 0.13641 0.00070 0.03853 0.30955 0.00449 0.08088 1.22364 0.03166 0.26990
60.13371 0.00040 0.02447 0.19733 0.00206 0.05792 0.40030 0.01428 0.11610 1.20911 0.04175 0.34190
7 0.12998 0.00075 0.02473 0.40703 0.00555 0.09827 0.68619 0.03434 0.21010 1.75139 0.05895 0.52140
8 0.02658 0.00087 0.00666 0.07491 0.00718 0.02506 0.47935 0.03283 0.15270 2.66295 0.16141 0.84520

288 E. Žic, P. Banko, L. Lešnik
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Summary
Hydraulic analysis of gate valve using
computational fluid dynamics (CFD). As
a very important element of most water
supply systems, valves are exposed to the
effects of strong hydrodynamic forces. When
exposed to large physical quantities, the
valve and piping can be damaged, which
could endanger the performance of a water
supply system. This is the main reason why
it is necessary to foresee and determine the
maximum values of velocity, pressure and
other physical quantities that can occur in the
system under certain conditions. Predicting
extreme conditions allows us to correctly
size the valve for the expected conditions to
which the valve might be exposed, which is
also the main objective of this paper. One of
the methods for predicting and determining
extreme values on a valve is to perform a sim-
ulation with computational fluid dynamics
(CFD). This is exactly the method used in
the preparation of this paper with the aim of
gaining insight into the physical magnitudes
for models of gate valves positioned inside
a pipe under characteristic degrees of valve
closure. The Ansys CFX 19.1 and Ansys Flu-
ent 19.1 software was used to simulate the
hydrodynamic analysis and obtain the re-
quired results. The hydrodynamic analysis
was performed for four opening degrees of
gate valve.
Authors’ address:
Elvis Žic
(https://orcid.org/0000-0002-5626-8394)
University of Rijeka
Faculty of Civil Engineering
Radmile Matejčić, 3, 51000, Rijeka
Croatia
e-mail: elvis.zic@uniri.hr